Hi All,

I have a problem with my existing brick chimney. The bricks on the top of the chimney are popping. About the top 8 feet. I am assuming it's from moisture getting behind the bricks. I recently caulked the cracks on the cap for a temporary fix. I am now thinking about installing brick veneer over the old bricks. I am planning on knocking off all the loose brick and replacing the cap. I just didn't want to have to remove all the old bricks. Is this a good idea?? Will the mortar hold? If I replace the chimney cap, will I still get moisture and bricks popping.

Please help me!

Thanks,
RFWWorker

 

When crown on chimney deteriorates, moisture tends to penetrate behind bricks and mortar. When water freezes, it expands. This can cause bricks to spall (surfaces pop off) and mortar to to loosen and fall out. Damaged bricks would have to be replaced. Getting an exact match would be a challenge. Mortar joints would have to be cleaned and and repointed. Chimney crown would need to be replaced and chimney capped. Cracked and deteriorating chimney crowns can cause much damage to chimney--both inside and out. Chimney caps provide additional protection for the crown. A professional chimney inspection is recommended to see if any damage has occurred to the interior of the chimney. Chimney crowns should be checked on a regular basis. There are new rubberized products available that are not so prone to deterioration.

 

It sounds like you have a very common situation for an older chimney. You are right about the probable cause. To be specific after the general suggestions -

1. Your caulking was a temporary fix, since the process of weathering has already taken place.

2. Do not apply new brick veneer over the old brick. You must have something to carry the load of the new brick. the logical method is to use the existing support.

3. Remove the damaged bricks and mortar. Chip or grind out any other mortar that appears to be soft or very sandy. Be careful to not damage or move the existing ceramic (clay) flues.

4. You may be able to find the same or similar brick for replacement. The appearance is up to you and the view of your chimney. You may opt for all new brick depending on the situation.

5. Use a Type N mortar (Quikrete, Sakrete, etc or mix your own) to lay the brick. You can use the same mortar to tuckpoint or repair the mortar joints you chipped out.

6. Do not try to reuse and old chimney cap since it is probably cracked. You can buy new caps with a proper overhang and drip ledge to prevent water from running down the face of the brick.

7. Caulk well and leave a soft joint between the flue and the brick. During normal cold weather operation, the brick will be cold (shrink) and the flue may be warm (expands), so a tight soft joint is necessary to prevent water penetration.

Good luck!!

Dick